The present invention relates to a semiconductor device including semiconductor chips packaged therein, and more particularly to a semiconductor device including semiconductor chips packaged therein with high density where the semiconductor chips are buried in a printed wiring board, and a method for fabricating such a semiconductor device.
In recent years, electronic equipment, in particular portable electronic equipment, has been downsized at rapid paces. To keep pace with this, downsizing of semiconductor devices is also in progress. For example, small-size semiconductor packages such as chip scale packages (CSP) have been commercialized. Also commercialized have been semiconductor packages in which semiconductor chips are stacked on top of each other to reduce the packaging area of the semiconductor chips. Moreover, for attainment of further thinned electronic equipment, there have been developed semiconductor devices including semiconductor chips packaged therein with high density where the semiconductor chips are buried in a multilayer wiring board.
Hereinafter, as a conventional example, a semiconductor device and a fabrication method thereof disclosed in Japanese Laid-Open Patent Publication No. 4-373157 will be described with reference to FIGS. 30A through 30C.
FIGS. 30A through 30C are cross-sectional views illustrating process steps of a conventional method for fabricating a semiconductor device.
As shown in FIG. 30A, an insulating board 13 having an opening 13a is bonded to the top surface of a first circuit board 10. The first circuit board 10 has first and second wirings 11 and 12 formed on the top and bottom surfaces thereof. A semiconductor chip 14 is mounted on the exposed top surface of the first circuit board 10 inside the opening 13a so that the circuit formation surface of the semiconductor chip 14 faces the top surface of the first circuit board 10, that is, by face-down bonding. To state more specifically, bumps 15, which are formed on electrodes (not shown) provided on the circuit formation surface of the semiconductor chip 14, are bonded to the first wiring 11 with conductive paste 16. A first resin layer 17 is then formed between the semiconductor chip 14 and the first circuit board 10.
As shown in FIG. 30B, a second resin layer 18 is formed on the sides and the top surface of the semiconductor chip 14 so that the opening 13a is filled completely. Thereafter, as shown in FIG. 30C, a second circuit board 20 is bonded to the top surfaces of the insulating board 13 and the second resin layer 18. The second circuit board 20 has third and fourth wirings 21 and 22 formed on the top and bottom surfaces thereof.
By the fabrication through the process steps shown in FIGS. 30A through 30C, completed is a semiconductor device where the semiconductor chip 14 is buried inside the multilayer circuit board composed of the first circuit board 10, the insulating board 13, the second circuit board 20, and the like.
The conventional semiconductor device described above has the following problems. The opening 13a must be formed through the insulating board 13 constituting the multilayer circuit board, to mount the semiconductor chip therein. This increases the number of fabrication steps and thus increases the cost. In addition, the first wiring 11 may be contaminated with an adhesive material and the like flowing out during the bonding of the insulating board 13 to the first circuit board 10. This makes it difficult to keep clean the connecting portions of the first wiring 11 with the semiconductor chip 14, and thus to ensure the electrical connection between the first wiring 11 and the semiconductor chip 14. Another problem is that separation is likely to occur at the interface between the insulating board .13 having the opening 13a and the second resin layer 18 filled in the opening 13a. This makes it difficult to attain a good-quality semiconductor device.
In order to reduce the thickness of the entire semiconductor device including semiconductor chips packaged therein, the semiconductor chips must be thin. A thin semiconductor chip is more susceptible to external damage and more easily warped losing flatness, compared with a thick semiconductor chip. Therefore, when a thin semiconductor chip is used for the conventional semiconductor device, difficulty arises during the formation of bumps and the mounting of the semiconductor chip in the board. In other words, in order to prevent a semiconductor chip from external damage and warping in the conventional semiconductor device, a thick semiconductor chip must be mounted. This increases the thickness of the multilayer circuit board constituting the conventional semiconductor device. In addition, since a thick semiconductor chip is buried with a resin in the multilayer circuit board, heat generated due to the operation of the semiconductor chip is less easily dissipated outside.
An object of the present invention is providing a thin semiconductor device with high reliability and high heat dissipation in which semiconductor chips are packaged with high density and, and a method for easily fabricating such a semiconductor device.
The first method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a semiconductor chip on a first surface of a substrate, the substrate having wiring formed on the first surface, so that a circuit formation surface of the semiconductor chip faces the first surface of the substrate and that an electrode provided on the circuit formation surface is connected with the wiring; (2) forming a sealing resin layer on the first surface of the substrate to cover the semiconductor chip; and (3) grinding the sealing resin layer and the semiconductor chip starting from a surface opposite to the circuit formation surface to thin the semiconductor chip.
According to the first method for fabricating a semiconductor device, a semiconductor chip is first mounted on the first surface of the substrate so that the circuit formation surface of the semiconductor chip faces the first surface of the substrate, and then the semiconductor chip is ground starting from the surface thereof opposite to the circuit formation surface, to be thinned. Accordingly, it is possible to handle the original thick semiconductor chip during the mounting of the semiconductor chip on the substrate. Thus, formation of the bumps on the semiconductor chip, the mounting of the semiconductor chip on the substrate, and the like can be performed easily and reliably while preventing occurrence of external damage and warp. Moreover, since the semiconductor chip mounted on the substrate is thinned by grinding, heat generated due to the operation of the semiconductor chip is easily dissipated. In addition, when such semiconductor chips are layered in a semiconductor device, the thickness of the resultant semiconductor device can be small. As a result, it is possible to easily fabricate a thin semiconductor device with high reliability and high heat dissipation in which semiconductor chips are packaged with high density.
According to the first method for fabricating a semiconductor device, the semiconductor chip is ground while being surrounded and sealed with a resin. This suppresses occurrence of external damage on the semiconductor chip due to the grinding, and thus a semiconductor device can be fabricated without deterioration in quality.
According to the first method for fabricating a semiconductor device, the semiconductor chip is mounted on the substrate and then covered with the resin layer. This simplifies the fabrication process compared with the conventional technique where an opening is formed through the insulating layer on the substrate and the semiconductor chip is buried in the opening together with the resin. This also prevents occurrence of the prior art problem of separation at the interface between the insulating layer having the opening and the resin layer filled in the opening, and thus a high-quality semiconductor device is attained.
In the first method for fabricating s semiconductor device, a filler made of an inorganic material is preferably mixed in the sealing resin layer.
The filler-mixed sealing resin layer has hardness closer to the hardness of the semiconductor chip, and this enables the sealing resin layer and the semiconductor chip to be ground simultaneously and uniformly. Thus, a high-quality semiconductor device is attained. Moreover, the filler serves to reduce the thermal expansion coefficient and curing shrinkage coefficient of the sealing resin layers. Therefore, the stress of the sealing resin layer acting on the semiconductor chip reduces, and thus warp of the semiconductor chip is made small. This enables fabrication of a higher-quality semiconductor device.
The first method for fabricating a semiconductor device preferably further includes the step of forming a resin layer between the substrate and the semiconductor chip between the step (1) and the step (2).
The above method prevents formation of a void-contained resin layer between the semiconductor chip and the substrate in the step (2) of forming the sealing resin layer covering the semiconductor chip. This improves the reliability of the semiconductor device.
In the first method for fabricating a semiconductor device, the step (2) preferably includes the step of forming the sealing resin layer under a pressure lower than the atmospheric pressure.
The above method suppresses generation of a void in the sealing resin layer covering the semiconductor chip, and thus improves the reliability of the semiconductor device.
In the method for fabricating a semiconductor device, the step (3) preferably includes the step of grinding the semiconductor chip and the sealing resin layer so as to be flush with each other.
The above method facilitates mounting of a new semiconductor chip or formation of a new insulating layer or wiring layer on the surface of the semiconductor chip or the sealing resin layer opposite to the circuit formation surface at a later stage.
In the first method for fabricating a semiconductor device, the step (3) preferably includes the step of recognizing a start position of grinding of the semiconductor chip by detecting a change in electrical resistance of grinding water containing chippings generated by the grinding of the semiconductor chip and the sealing resin layer.
By the above method, the variation in the thickness of the ground semiconductor chip can be reduced. Therefore, a small target value can be set for the thickness of the ground semiconductor chip, and thus the thickness of the ground semiconductor chip can be further reduced.
In the method for fabricating a semiconductor device, the step (3) preferably includes the step of recognizing a start position of grinding of the semiconductor chip by detecting a change in grinding drag acting on a grinder for grinding the semiconductor chip and the sealing resin layer.
By the above method, the variation in the thickness of the ground semiconductor chip can be reduced. Therefore, a small target value can be set for the thickness of the ground semiconductor chip, and thus the thickness of the ground semiconductor chip can be further reduced.
In the method for fabricating a semiconductor device, the step (3) preferably includes the step of recognizing a start position of grinding of the semiconductor chip by irradiating the semiconductor chip and the sealing resin layer with light and detecting a change in reflection amount or absorption amount of the light.
By the above method, the variation in the thickness of the ground semiconductor chip can be reduced. Therefore, a small target value can be set for the thickness of the ground semiconductor chip, and thus the thickness of the ground semiconductor chip can be further reduced.
The method for fabricating a semiconductor device preferably further includes the step of forming an insulating layer on a surface opposite to the circuit formation surface of the semiconductor chip after the step (3).
The above method protects the semiconductor chip against external damage, and electrically protects the semiconductor chip by insulating the semiconductor chip from a wiring layer that may be newly formed on the surface of the semiconductor chip opposite to the circuit formation surface at a later stage. The above method therefore simplifies handling of the semiconductor device including a thin semiconductor chip packaged therein.
When an insulating layer is formed on a surface opposite to the circuit formation surface of the semiconductor chip, the insulating layer is preferably made of a material different from a material of the sealing resin layer.
By using a different material, the insulating layer and the sealing resin layer can be different from each other in characteristics such as resin flow filling ability, thickness uniformity, adhesion, mechanical strength, and the like. This enables easy fabrication of a high-quality semiconductor device.
When an insulating layer is formed on a surface opposite to the circuit formation surface of the semiconductor chip, the insulating layer is preferably formed by curing a resin in resin-added copper foil.
By using resin-added copper foil, when wiring is formed on the surface of the semiconductor chip opposite to the circuit formation surface, a conductive film to be patterned into the wiring can be formed simultaneously with the formation of the insulating layer that electrically protects the semiconductor chip. This simplifies the fabrication process and thus enables efficient fabrication of the semiconductor device.
The first method for fabricating a semiconductor device preferably further includes the step of forming a conductive layer on a surface opposite to the circuit formation surface of the semiconductor chip after the step (3).
By the above method, if a metal material or the like is used as the conductive layer, the thermal conductivity of the conductive layer can be increased, and thus heat generating during the operation of the semiconductor chip can be efficiently dissipated outside. In addition, it becomes easy to secure the substrate potential at the semiconductor chip via the conductive layer.
The first method for fabricating a semiconductor device preferably further includes the step of forming an external connection terminal on a surface of the sealing resin layer or the semiconductor chip opposite to the circuit formation surface, or on a second surface of the substrate, after the step (3).
By the above method, it is possible to electrically and mechanically connect another electrical component to the external connection terminal. In this way, a good-quality, large-scale, multi-function electric circuit system can be efficiently attained.
The method for fabricating a semiconductor device preferably further includes the step of forming a first external connection terminal on a surface of the sealing resin layer or the semiconductor chip opposite to the circuit formation surface, and a second external connection terminal on a second surface of the substrate, after the step (3), wherein the first external connection terminal and the second external connection terminal are located in the same region when viewed from a position above the first surface of the substrate.
By the above method, it is possible to electrically and mechanically connect a plurality of semiconductor devices fabricated by the first method for fabricating a semiconductor device by stacking them on top of each other. In this way, a good-quality, large-scale, electric circuit system can be efficiently attained.
The second method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a first semiconductor chip on a first surface of a substrate, the substrate having first wiring formed on the first surface, so that a first circuit formation surface of the first semiconductor chip faces the first surface of the substrate and that a first electrode provided on the first circuit formation surface is connected with the first wiring; (2) forming a first sealing resin layer on the first surface of the substrate to cover the first semiconductor chip; (3) grinding the first sealing resin layer and the first semiconductor chip starting from a surface opposite to the first circuit formation surface to thin the first semiconductor chip; (4) forming second wiring on a surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface; (5) mounting a second semiconductor chip on the surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface so that a second circuit formation surface of the second semiconductor chip faces the first surface of the substrate and that a second electrode provided on the second circuit formation surface is connected with the second wiring; (6) forming a second sealing resin layer on the surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface to cover the second semiconductor chip; and (7) grinding the second sealing resin layer and the second semiconductor chip starting from a surface opposite to the second circuit formation surface to thin the second semiconductor chip.
The second method for fabricating a semiconductor device can provide the effect that the semiconductor device including layered semiconductor chips can be thinned without fail, in addition to the effects obtained in the first method for fabricating a semiconductor device.
In the second method for fabricating a semiconductor device, the first semiconductor chip and the second semiconductor chip are preferably the same in the number of terminals and the positions of the terminals.
By the above method, it is possible reduce the length of the wiring connecting the semiconductor chips, and thus the wiring pattern can be simplified.
The third method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a first semiconductor chip on a first surface of a substrate, the substrate having first wiring formed on the first surface and second wiring formed on a second surface, so that a first circuit formation surface of the first semiconductor chip faces the first surface of the substrate and that a first electrode provided on the first circuit formation surface is connected with the first wiring; (2) forming a first sealing resin layer on the first surface of the substrate to cover the first semiconductor chip; (3) grinding the first sealing resin layer and the first semiconductor chip starting from a surface opposite to the first circuit formation surface to thin the first semiconductor chip; (4) mounting a second semiconductor chip on the second surface of the substrate so that a second circuit formation surface of the second semiconductor chip faces the second surface of the substrate and that a second electrode provided on the second circuit formation surface is connected with the second wiring; (5) forming a second sealing resin layer on the second surface of the substrate to cover the second semiconductor chip; and (6) grinding the second sealing resin layer and the second semiconductor chip starting from a surface opposite to the second circuit formation surface to thin the second semiconductor chip.
The third method for fabricating a semiconductor device can provide the effect that the semiconductor device including layered semiconductor chips can be thinned without fail, in addition to the effects obtained in the first method for fabricating a semiconductor device. In addition, the resin layers covering the semiconductor chips are formed symmetrically with respect to the substrate. This balances the shrinkage of the resin layers on both surfaces of the substrate and thus serves to minimize the amount of warp of the semiconductor devices.
In the second or third method for fabricating a semiconductor device, the first semiconductor chip and the second semiconductor chip are preferably located in the same region when viewed from a position above the first surface of the substrate.
By the above method, it is possible to reduce the plan dimensions of the semiconductor device including semiconductor chips packaged therein. Specifically, it is possible to attain a semiconductor device that has plan dimensions close to those of the semiconductor chips and realizes a packaging density as high as that of a CSP.
In the third method for fabricating a semiconductor device, the step (3) is preferably performed in the state where the second wiring has not been formed on the second surface of the substrate.
By the above method, it is possible to minimize the unevenness of the second surface of the substrate that is opposite to the surface to be ground of the substrate including the semiconductor chip. It is therefore possible to grind the surface to be ground uniformly and thus suppress generation of damage and the like in the semiconductor chip. As a result, a good-quality semiconductor device can be fabricated.
In the third method for fabricating a semiconductor device, the step (3) is preferably performed in the state where a conductive film is formed on the second surface of the substrate and has not yet been patterned into the second wiring.
By the above method, it is possible to minimize the unevenness of the second surface of the substrate that is opposite to the surface to be ground of the substrate including the semiconductor chip. It is therefore possible to grind the surface to be ground uniformly and thus suppress generation of damage and the like in the semiconductor chip. As a result, a good-quality semiconductor device can be fabricated.
The third method for fabricating a semiconductor device preferably further includes the step of covering the surface of the first semiconductor chip opposite to the first circuit formation surface and the surface of the second semiconductor chip opposite to the second circuit formation surface with a resin film simultaneously, after the step (6).
By the above method, the fabrication process can be simplified, and thus the semiconductor device can be efficiently fabricated.
The fourth method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a plurality of semiconductor chips each for each of a plurality of regions on a first surface of a substrate, the substrate having a plurality of wirings each formed for each of the plurality of regions on the first surface, so that circuit formation surfaces of the respective semiconductor chips face the first surface of the substrate and that electrodes provided on the circuit formation surfaces are respectively connected with the plurality of wirings; (2) forming a sealing resin layer on the first surface of the substrate to cover the plurality of semiconductor chips; (3) grinding the sealing resin layer and the plurality of semiconductor chips starting from surfaces opposite to the circuit formation surfaces to thin the plurality of semiconductor chips; and (4) dividing the substrate including the plurality of thinned semiconductor chips into the plurality of regions.
The fourth method for fabricating a semiconductor device can provide the effect that a small semiconductor device having plan dimensions close to those of the semiconductor chips can be fabricated simply in large quantity, in addition to the effects obtained in the first method for fabricating a semiconductor device.
The fifth method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a plurality of first semiconductor chips each for each of a plurality of regions on a first surface of a substrate, the substrate having a plurality of first wirings each formed for each of the plurality of regions on the first surface, so that first circuit formation surfaces of the respective first semiconductor chips face the first surface of the substrate and that electrodes provided on the first circuit formation surfaces are respectively connected with the plurality of first wirings; (2) forming a first sealing resin layer on the first surface of the substrate to cover the plurality of first semiconductor chips; (3) grinding the first sealing resin layer and the plurality of first semiconductor chips starting from surfaces opposite to the first circuit formation surfaces to thin the plurality of first semiconductor chips; (4) forming a plurality of second wirings each for each of the plurality of regions on a surface of the first sealing resin layer or the surfaces of the plurality of first semiconductor chips opposite to the first circuit formation surfaces; (5) mounting a plurality of second semiconductor chips each for each of the plurality of regions on the surface of the first sealing resin layer or the surfaces of the plurality of first semiconductor chips opposite to the first circuit formation surfaces so that second circuit formation surfaces of the respective second semiconductor chips face the first surface of the substrate and that second electrodes provided on the second circuit formation surfaces are respectively connected with the plurality of second wirings; (6) forming a second sealing resin layer on the surface of the first sealing resin layer or the surfaces of the plurality of first semiconductor chips opposite to the first circuit formation surfaces to cover the plurality of second semiconductor chips; (7) grinding the second sealing resin layer and the plurality of second semiconductor chips starting from surfaces opposite to the second circuit formation surfaces to thin the plurality of second semiconductor chips; and (8) dividing the substrate including the plurality of thinned second semiconductor chips into the plurality of regions.
The fifth method for fabricating a semiconductor device can provide the effect that a small semiconductor device having plan dimensions close to those of the semiconductor chips can be fabricated simply in large quantity, in addition to the effects obtained in the second method for fabricating a semiconductor device.
The sixth method for fabricating a semiconductor device of the present invention includes the steps of: (1) mounting a plurality of first semiconductor chips each for each of a plurality of regions on a first surface of a substrate, the substrate having a plurality of first wirings each formed for each of the plurality of regions on the first surface and a plurality of second wirings each formed for each of the plurality of regions on a second surface, so that first circuit formation surfaces of the respective first semiconductor chips face the first surface of the substrate and that electrodes provided on the first circuit formation surfaces are respectively connected with the plurality of first wirings; (2) forming a first sealing resin layer on the first surface of the substrate to cover the plurality of first semiconductor chips; (3) grinding the first sealing resin layer and the plurality of first semiconductor chips starting from surfaces opposite to the first circuit formation surfaces to thin the plurality of first semiconductor chips; (4) mounting a plurality of second semiconductor chips each for each of the plurality of regions on the second surface of the substrate so that second circuit formation surfaces of the respective second semiconductor chips face the second surface of the substrate and that second electrodes provided on the second circuit formation surfaces are respectively connected with the plurality of second wirings; (5) forming a second sealing resin layer on the second surface of the substrate to cover the plurality of second semiconductor chips; (6) grinding the second sealing resin layer and the plurality of second semiconductor chips starting from surfaces opposite to the second circuit formation surfaces to thin the plurality of second semiconductor chips; and (7) dividing the substrate including the plurality of thinned second semiconductor chips into the plurality of regions.
The sixth method for fabricating a semiconductor device can provide the effect that a small semiconductor device having plan dimensions close to those of the semiconductor chips can be fabricated simply in large quantity, in addition to the effects obtained in the third method for fabricating a semiconductor device.
The first semiconductor device of the present invention includes: a semiconductor chip mounted on a first surface of a substrate, the substrate having wiring formed on the first surface, so that a circuit formation surface of the semiconductor chip faces the first surface of the substrate and that an electrode provided on the circuit formation surface is connected with the wiring; and a sealing resin layer formed on the first surface of the substrate to cover the semiconductor chip and also be flush with a surface of the semiconductor chip opposite to the circuit formation surface.
The first semiconductor device is formed by the first or fourth fabrication method of the present invention, and therefore provides substantially the same effects as those provided by the first or fourth fabrication method.
The first semiconductor device preferably further includes an insulating layer formed on the surface of the semiconductor chip opposite to the circuit formation surface.
The above construction protects the semiconductor chip against external damage, and also electrically protects the semiconductor chip by insulating the semiconductor chip from a wiring layer that may be formed on the surface of the semiconductor chip opposite to the circuit formation surface at a later stage. This simplifies handling of the semiconductor device including a thin semiconductor chip packaged therein.
The first semiconductor device preferably further includes a conductive layer formed on the surface of the semiconductor chip opposite to the circuit formation surface.
With the above construction, if a metal material or the like is used as the conductive layer, the thermal conductivity of the conductive layer can be increased, and thus heat generating during the operation of the semiconductor chip can be efficiently dissipated outside. In addition, it becomes easy to secure the substrate potential at the semiconductor chip via the conductive layer.
The first semiconductor device preferably further includes an external connection terminal formed on a surface of the sealing resin layer or the semiconductor chip opposite to the circuit formation surface, or on a second surface of the substrate.
With the above construction, it is possible to electrically and mechanically connect another electrical component to the external connection terminal. In this way, a good-quality, large-scale, multi-function electric circuit system can be efficiently attained.
The first semiconductor device further includes a first external connection terminal formed on a surface of the sealing resin layer or the semiconductor chip opposite to the circuit formation surface; and a second external connection terminal formed on a second surface of the substrate, wherein the first external connection terminal and the second external connection terminal are located in the same region when viewed from a position above the first surface of the substrate.
With the above construction, it is possible to electrically and mechanically connect a plurality of first semiconductor devices by stacking them on top of each other. In this way, a good-quality, large-scale, electric circuit system can be efficiently attained.
The second semiconductor device of the present invention includes: a first semiconductor chip mounted on a first surface of a substrate, the substrate having first wiring formed on the first surface, so that a first circuit formation surface of the first semiconductor chip faces the first surface of the substrate and that a first electrode provided on the first circuit formation surface is connected with the first wiring; a first sealing resin layer formed on the first surface of the substrate to cover the first semiconductor chip and also be flush with a surface of the first semiconductor chip opposite to the first circuit formation surface; second wiring formed on a surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface; a second semiconductor chip mounted on the surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface so that a second circuit formation surface of the second semiconductor chip faces the first surface of the substrate and that a second electrode provided on the second circuit formation surface is connected with the second wiring; and a second sealing resin layer formed on the surface of the first sealing resin layer or the first semiconductor chip opposite to the first circuit formation surface to cover the second semiconductor chip and also be flush with a surface of the second semiconductor chip opposite to the second circuit formation surface.
The second semiconductor device is formed by the second or fifth fabrication method of the present invention, and therefore provides substantially the same effects as those provided by the second or fifth fabrication method.
In the second semiconductor device, the first semiconductor chip and the second semiconductor chip are preferably the same in the number of terminals and the positions of the terminals.
With the above construction, it is possible reduce the length of the wiring connecting the semiconductor chips, and thus the wiring pattern can be simplified.
The third semiconductor device of the present invention includes: a first semiconductor chip mounted on a first surface of a substrate, the substrate having first wiring formed on the first surface and second wiring formed on a second surface, so that a first circuit formation surface of the first semiconductor chip faces the first surface of the substrate and that a first electrode provided on the first circuit formation surface is connected with the first wiring; a first sealing resin layer formed on the first surface of the substrate to cover the first semiconductor chip and also be flush with a surface of the first semiconductor chip opposite to the first circuit formation surface; a second semiconductor chip mounted on the second surface of the substrate so that a second circuit formation surface of the second semiconductor chip faces the second surface of the substrate and that a second electrode provided on the second circuit formation surface is connected with the second wiring; and a second sealing resin layer formed on the second surface of the substrate to cover the second semiconductor chip and also be flush with a surface of the second semiconductor chip opposite to the second circuit formation surface.
The third semiconductor device is formed by the third or sixth fabrication method of the present invention, and therefore provides substantially the same effects as those provided by the third or sixth fabrication method.
In the second or third semiconductor device, the first semiconductor chip and the second semiconductor chip are preferably located in the same region when viewed from a position above the first surface of the substrate.
With the above construction, it is possible to reduce the plan dimensions of the semiconductor device including layered semiconductor chips packaged therein. Specifically, it is possible to realize a packaging density as high as that of a CSP that has plan dimensions close to those of the semiconductor chips.